The present disclosure relates generally to the field of three-dimensional imaging. The present invention more particularly relates to the field of stereoscopic and autostereoscopic displays.
Stereoscopic imaging is a technique for creating a three-dimensional scene or the illusion of depth by presenting a different image to each eye. An autostereoscopic display creates the three-dimensional scene or illusion of depth using a flat screen or imaging device and does not require the use of special glasses by the viewer to view the depth. Some autostereoscopic displays utilize the layering of multiple flat liquid crystal displays (LCDs) to provide the different images for each eye.
Layering image forming devices such as LCDs is known to create an interference pattern of bright and dark bands (commonly referred to as moiré interference fringes) across the viewable area of the display. This problem has been addressed in the prior art by placing a holographic diffuser in front of and spaced apart from the layered image forming devices. The space between the holographic diffuser and the layered image forming device has conventionally been provided by an air gap. Such an approach presents challenges when the display is used in harsh environments such as military and defense applications.
The nature of holographic diffusers with their delicate surface topology prevents the diffusion surface from being coupled to the display stack. In addition, the presence of an air gap in between the holographic diffuser and the layered display allows for foreign particles or water condensation to appear between the display surface and the diffusing surface. Damage to the display assembly may also occur in an air gap construction due to the independent vibration displacement of the uncoupled substrates. This may result in degraded image quality for the viewer along with potential damage to the diffusion surface during use in rugged environments.
What is needed is a new display for three dimensional imaging that provides reduced interference patterns while maintaining, for example, legibility and spatial resolution of images on the display.